The present invention relates to an improved apparatus for stitching or stapling a group of collated signatures to form a book or magazine.
Prior to the present invention collated groups of signatures have been conveyed through a stitcher assembly which stapled together collated groups of signatures. The stitcher assembly includes a conventional stitcher head disposed above the path of movement of the signatures and a conventional clincher disposed below the path of movement of the signatures. The stitcher head bends a short piece of wire to form a staple and drives it through the collated signatures, and the clincher folds the ends of the staple to finish the stitching operation. Examples of known stitcher heads and clinchers can be found in U.S. Pat. Nos. 1,252,011; 1,302,402; 1,983,384; and 3,514,027.
It has been a practice to mount stitcher assemblies on a frame which is driven in a reciprocating motion parallel to the path of the conveyor. As groups of collated signatures move downstream through the stitching machine, the frame and the stitcher assembly mounted on it move together with each group of signatures as the stitching operation is performed. The stitching occurs in effect "on the fly", i.e., while the group of signatures is moving. The stapled signatures leave the machine while the reciprocating frame returns upstream before stitching the next group of signatures.
The reciprocating motion of the frame has commonly been accomplished by use of a crank and connecting rod. The crank has been driven in synchronism with the conveyor, and the connecting rod is connected between a crank pin and the reciprocating frame. Cams and cam followers have also been used to drive the frame in a reciprocating motion and to actuate the stitcher head and clincher. Examples of such mechanisms may be found in the above mentioned U.S. Pat. No. 3,514,027; and in U.S. Pat. Nos. Re 13,967; 2,827,632; 1,608,838; and 1,534,141.
Further, it has been a conventional practice to mount the reciprocating frame on ways or rails which guide the frame for linear motion. Various types of ways or rails have been used, including slots or grooves formed in a fixed member which extends parallel to the path of the signature conveyor. The patents mentioned above in connection with mechanisms for driving a reciprocating frame also disclose various types of guides for supporting the frame.
The use of these means for guiding the reciprocating frame has presented various difficulties. The ways or rails are exposed and may collect dirt and grit which cause excessive wear. Use of rails results in relatively large amounts of friction so that a correspondingly large amount of power is required to reciprocate the frame. In addition, difficulties have been encountered in fabricating rails which are parallel and in maintaining parallelism over a large number of operating cycles.
The present invention provides a new and improved collating machine in which a stitcher assembly is mounted to a reciprocating frame. The reciprocating frame is guided for substantially linear motion by two suspension units. The suspension units are mounted in tandem to the base of the collating machine. The suspension units eliminate the guides or slides of conventional collating machines, and thus overcome the difficulties inherent in those systems and mentioned above.
Each suspension unit includes two suspension links and coupler link. In each suspension unit the upper ends of the suspension links are pivotably connected with the collating machine's base and the lower ends are pivotably connected with opposite ends of the base of the coupler link. The suspension links support the coupler links for rocking motion about a central position in which the bases of the coupler links are substantially horizontal.
Each coupler link includes an upstanding pedestal to which the reciprocating frame is connected. The pedestal is fixedly connected to the base of the coupler link and extends upwardly from the base midway between the connections between the base and the lower ends of the suspension links. The upper end portion of the pedestal is a pivotable connected with the reciprocating frame. It is a characteristic of the suspension units that when the coupler link rocks about its central position, the upper end portion of the pedestal travels along a substantially straight line.